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取过２０ 目筛黄筋泥（浙江龙游县， 桔园表层土，ｐＨＨ２０ 为５．１，有机质含量为２．３５％ ， 每１００ ｇ 土的阳离子交换量为１０．５０ ｍｍｏｌ， 每１ ｋｇ 土的可溶态稀土总量为１１．４４ ｍｇ） 风干土若干， 以０，１０，５０，１００，２００，３５０ ｍｇ·ｋｇ－１的浓度水平分别加入混合稀土及单一稀土元素Ｐｒ，Ｓｍ ，Ｅｕ 等， 混合稀土的配比为Ｌａ∶Ｃｅ∶Ｐｒ∶Ｎｄ∶Ｓｍ∶Ｅｕ∶Ｇｄ∶Ｙ＝４∶４∶２∶２∶２∶１∶１∶４， 并对土样加蒸馏水至田间持水量的５０％ ， 保持１００％ 的湿度在生化培养箱中于２５ ℃下恒温培养一周后进行微生物量的测定， 每个样重复３ 次， 土壤样品微生物量碳的测定方法采用氯仿熏蒸，０．５ ｍｏｌ·Ｌ－１ Ｋ２ＳＯ４ 提取法， 提取液中的有机碳浓度用自动定碳仪（ＴＯＣ）测定， 并由下式计算微生物量：ＳＭＢＣ＝ （ｃＥＣｔ－ ｃＥＣＯ）／０．４５， 式中，ＳＭＢＣ为土壤微生物量碳，ｃＥＣＯ，ｃＥＣｔ分别为氯仿熏蒸前后提取液中有机碳的浓度。测定结果表明， 不同稀土元素对土壤熏蒸前后的有机碳含量及其微生物量碳变化的影响规律基本相似， 随着稀土浓度的升高，熏蒸前后有机碳的含量都有不同程度的升高， 而且两者在量值上有逐渐
Take 20 mesh sieve of yellow bar mud (Zhejiang Longyou County, Orange Garden surface soil, pHH20 is 5.1, organic matter content of 2.35%, cation exchange capacity per 100 g of soil 10.50 mmol, 1 kg The total amount of soluble rare earths in the soil was 11.44 mg). A number of dry soils were added to the mixed rare earths and the single rare earth elements Pr, Sm at concentrations of 0, 10, 50, 100, 200 and 350 mg · kg-1 respectively. Eu, etc., the ratio of rare earth mixed La: Ce: Pr: Nd: Sm: Eu: Gd: Y = 4: 4: 2: 2: 2: 1: 1: 4, and soil samples were distilled water to the field 50% water, maintaining 100% humidity in a biochemical incubator incubated at 25 ° C for one week after the determination of microbial biomass, each sample was repeated 3 times, the determination of soil microbial biomass carbon fumigation with chloroform, 5 mol·L-1 K2SO4 extraction method, the concentration of organic carbon in the extract was determined with automatic carbon analyzer (TO C), and the microbial biomass was calculated from the following formula: SMBC = (cECt-cECO) /0.45, where SMBC is soil microbial biomass carbon, cECO and cECt are the concentrations of organic carbon in the extract before and after chloroform fumigation, respectively. The results showed that the effect of different rare earth elements on the organic carbon content and microbial biomass carbon before and after soil fumigation were basically similar. With the increase of rare earth concentration, the content of organic carbon increased before and after fumigation, and Both have a gradual increase in magnitude